Private speech: four studies and a review of theories.
D000367:Age Factors; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D003071:Cognition; D004454:Echolalia; D004532:Ego; D005260:Female; D006801:Humans; D007360:Intelligence; D007398:Interpersonal Relations; D007804:Language Development; D008297:Male; D010379:Peer Group; D011582:Psychological Theory; D012919:Social Behavior; D013060:Speech; D014705:Verbal Behavior